In a Long Term Evolution (LTE) system, to support a hybrid automatic repeat request (HARQ), user equipment needs to feedback, to a base station by using a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH), a hybrid automatic repeat request-acknowledgment (HARQ-ACK) corresponding to a physical downlink shared channel (PDSCH). The HARQ-ACK may be referred to as an acknowledgement (ACK) or a negative acknowledgement (NACK). The user equipment needs to receive, by using a physical hybrid automatic repeat request indicator channel (PHICH), a HARQ-ACK corresponding to the PUSCH.
An existing LTE system includes two types of frame structures. A first type of frame structure is used for frequency division duplex (FDD), and a second type of frame structure is used for time division duplex (TDD). A length of each subframe in the two types of frame structures is 1 ms.
The frame structure applied to the TDD includes a downlink subframe, an uplink subframe, and a special subframe. There are multiple uplink-downlink configurations in the existing system. For different uplink-downlink configurations, quantities and locations of downlink subframes, uplink subframes, and special subframes in each frame are different. The different uplink-downlink configurations are corresponding to different HARQ timings. The HARQ timings are not unified, so that implementation complexity and standard protocol complexity are relatively high.